Roasting-kiln having superposed vaulted hearths.



1, LUTJENS & w. LUDEWIG.

ROASTING KILN HAVING SUPERPOSED VAULTED HEARTHS. APPLICATION FILED OCT. 26. 1912.

' 1,176,070. v Patented Mar. 21,1916.

THE COLUMBIA PLANDGRAPH co., WASHINGTON, D. c.

Arrus r ROASTING-KILN HAVING SUPERPOSED VAULTED HEARTHS.

Specification of Letters Patent.

Patented Mar. 21, 1916.

Application filed October 26, 1912. Serial No. 727,900.

To all whom it may oncern Be it known that we, JACOB Lf'rrJENs and VVILHELM LUDEWIG, subjects of the German Empire, and residents of Hanover, Germany, have invented certain new and useful Improvements in Roasting-Kilns Having superposed Vaulted Hearths, of which the following is a specification accompanied by drawings 7 The present invention relates to a roasting kiln with several superposed vaulted hearths and mechanical raker and consists essentially in the arms of the mechanical raker being curved to correspond with the vault of the hearth. The object of such arrangement is to insure a layer of ores of uniform thickness on the vaulted hearths. hen straight raker arms are used as heretofore the layer of ores is thicker at the outer circumference than in the center where the lower edges of the rabbles of the straight raker arms are separated from the vaulted surface of the hearth by the least distance. In case a pyrites-ore is to be treated, which for instance contains copper and will therefore melt easily andslag, such slag will naturally be formed quickest at those points where the layer of ore is the thickest, while the elastic bolster will be absent at the thinner portion of the layer, in which bolster the slag would, so to speak, embed itself and so escape the continuous action of the raker rabbles. As soon as a crust of slag has been formed, it will quickly increase and will then form a solid and very troublesome obstruction in the kiln. A thick cake of slag is also frequently very difficult to detach and remove.

The present invention not only avoids the above said troubles, but will also afford the advantage, that the height of the kiln can be considerably reduced, as the curved arms require less space than the straight ones. This is a very important feature as in recent times large kilns for a charge of 12, 15 and even 18 tons of pyrites are being called for.

In a kiln constructed according to the present invention the hearths are closer to each other and the heat radiated from the Copies of this patent may be obtained for vault to the charge is greater; the heat is therefore better utilized and the roasting is favorably influenced. As the height will be less, there will be a saving in building material and at the same time it will be possible to employ a larger radius for the vault and thereby render the latter steadier, reduce the pressure, cheapen the anchorage and above all give the kiln a longer life.

The raker arms may be arranged either with the rabbles cast in one piece with them or with interchangeable rabbles. In the latter instance the clear space between the rabbles will be curved to the same radius as the arms, so that the interchanging of the rabbles will be facilitated. The arms are preferably made of steel castings and the rabbles should be of substantially equal size and length and should extend radially from the raker arms.

In the accompanying drawing the present invention is shown in a vertical section taken through a kiln with a plurality of superposed hearths having raker arms curved according to the vaulted hearths.

The vaulted hearths of the kiln are indicated by the letter a. The vaults themselves are indicated by the letter 6. The raker arms 0 are shown without rabbles, and the arms (I with radially extending rabbles. These rabbles may be either cast in one piece with the arms or be interchangeable.

We claim:

In a roasting kiln having superposed vaulted hearths and mechanical rakers, the improvement in the rakers, comprising raker arms curved or bowed to substantially conform to the curvature of the hearth surface, and radially extending rabbles of substantially equal size and length carried by said arms.

In testimony whereof we have signed this specification in the presence of two subscribing witnesses.

JACOB LIITJ ENS. WILI-IELM LUDEVVIG.

Witnesses:

ROBERT H. HINCKLEY, MINNA CAssEL,

five cents each, by addressing the Commissioner of Patents,

Washington, D. G. 

